Abstract
Background: Mycoplasma is a significant microorganism of poultry, which can cause respiratory infections and synovial inflammation, bringing about huge financial misfortunes to poultry workmanship worldwide.
Aim: The goal of existing research was to determine the infection rate of Mycoplasma gallisepticum (MG) from chronic respiratory disease (CRD) cases among broilers fields in Mosul/ Iraq using the polymerase chain reaction (PCR) technique.
Methods: All 92 lungs samples were collected from broilers with classical respiratory signs in different regions of the Nineveh governorate for three months from February to April 2021.PCR tests were performed using two couple primers, one for the qualitative amplification of 16S rRNA genes (285 base pairs) in Mycoplasma spp. and the second couple for detection of M. gallisepticum (580 base pairs).
Results: Among the samples obtained from broilers, 87 (94.7%) were positive for Mycoplasma, and 79 (85.9%) were positive for M. gallisepticum.
Conclusion: Our results showed that MG infection in broiler chickens leads to serious clinical symptoms and severe lesions. The rate of Mycoplasma isolation in this study is high despite the short lifespan of broiler chickens.

Key words: Mycoplasma gallisepticum, Broiler, Chronic respiratory disease, PCR.